1. Field of the Invention
The present invention relates to a pump which transports a liquid having a conductivity, and a liquid transporting apparatus which is provided with the pump, and a liquid moving apparatus which moves a liquid having a conductivity.
2. Description of the Related Art
An ink supply pump which supplies ink to an ink-jet head which discharges a conductive ink onto a paper, is available as a pump which applies pressure on a liquid having conductivity, and various types of pumps are hitherto used for this ink supply pump. For example, U.S. Pat. No. 6,637,872 B2 (FIGS. 7 and 8) corresponding to Japanese Patent Application Laid-open No. 2001-310477, describes a tube pump which applies pressure to ink in a tube by pressing two rollers fixed to a roller holder which rotates. U.S. Pat. No. 6,637,872 B2 also describes a diaphragm pump which applies pressure to the ink in a housing by transmitting a torque of a cam to a diaphragm via a compressed coil spring.
However, since the ink supply pump of U.S. Pat. No. 6,637,872 B2 includes movable parts such as the rotating roller holder and the cam, it is necessary to have these movable parts, a structure to drive these parts, and furthermore a structure to transmit a rotational energy of the movable parts. As a result, the structure of the pump becomes complicated and the number of components is increased. Moreover, a noise generated during the rotary drive of the moving parts is high. Furthermore, a substantial amount of energy is required for the rotary drive of the moving parts and it is not favorable also in view of the running cost.